Multiple Feed and Multiple Discharge Refiner

ABSTRACT

A refiner for refining lignocellulose containing fiber material has two substantially oppositely positioned refining elements (6, 6a, 6b, 9) with refining surfaces (8, 8a, 8b, 11, 11a, 11b) with blade bars (25, 27) and grooves (26, 28). Opposed refining surfaces face each other forming a refining chamber (15, 15a, 15b) which receives fiber material to be refined. The refiner has two feed channels (19a, 19b) for feeding into the refiner at least one fiber material fraction (FM1, FM2) to be refined, and two refining zones (21a, 21b) with at least one different refining surface characteristic between the refining zones (21a, 21b). Each refining zone (21a, 21b) is intended to refine one fiber material fraction (FM1, FM2) of the at least one fiber material fraction (FM1, FM2). There is at least one discharge channel (23, 23a, 23b) for discharging out of the refiner at least one flow of refined material.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority on Finnish App. No. FI 20195865, filed Oct. 10, 2019, the disclosure of which is incorporated by reference herein.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates to a refiner and a method for refining lignocellulose-containing fiber material.

In paper and board manufacturing one or more lignocellulose-containing wood-based fiber material fractions of different quality may be mixed for manufacturing the paper or board web. The mixing of the fiber material fractions of different quality takes place for example due to a need to obtain a combination of various kinds of properties in the end product, such as a specific tensile strength with a specific grammage. The fiber material fractions of different quality may include for example virgin hardwood and softwood-based fiber pulps as well as different recycled fiber materials, such as long-fibered and short-fibered pulps made of OCC (Old Corrugated Container).

Commonly the mixed pulp is manufactured by mixing at least two fiber material fractions of different quality from separate storage tanks, each specific storage tank being reserved for the single fiber material fraction of specific quality. However, single fiber material may also contain different qualities, such as OCC that contains both long-fibered fraction and short-fibered fraction. When considering refining of the fiber material taking place before supplying the refined fiber material to the storage tank, each different fiber material fraction is refined with a refiner specifically designed for having refining surface characteristics optimized for that specific fiber material fraction. This means that each refined fiber material fraction has high quality but the number of the refiners increases with the number of different fiber material fractions to be mixed.

The number of the refiners may be reduced by first mixing at least two fiber material fractions of different quality with each other, or having one fiber material with a large fiber length distribution, like the OCC, and thereafter refining the fiber material pulp with a single refiner. However, in this case the refining surface characteristics of the refiner are a compromise based on the refining needs of the fiber material fractions forming the pulp. Therefore, the quality of the mixed pulp after refining is not necessarily as high as the quality of the pulp formed by mixing at least two separately refined fiber material fractions as disclosed above.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a novel refiner and a method for refining lignocellulose-containing fiber material.

The idea of the invention is to simultaneously refine with a single refiner at least two flows of at least one fiber material fraction at different refining zones in the single refiner, refining surface characteristics of the different refining zones being specifically designed in view of the fiber material fraction to be refined at the refining zone as well as in view of the intended refining effect to be subjected to the fiber material fraction at the refining zone. It is thus possible to feed into the refiner at least two flows of fiber material, which two flows may be either one and the same fiber material fraction or different fiber material fractions of different qualities.

An advantage of the invention is that it is possible with a single refiner to refine simultaneously at least one fiber material fraction with different refining effects to be subjected to the at least one fiber material fraction, whereby the fiber material portions subjected to the different refining effects may for example be directed to different layers in the paper or board web to be manufactured or into different processes. The refiner of this kind is especially useful in applications wherein required amounts or volumes of different fiber material fractions for the production of the paper or board are moderate.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings.

FIG. 1 shows schematically a side view of a conical refiner partly in cross section.

FIG. 2 shows schematically a plane figure of a blade element applicable to be used in the conical refiner of FIG. 1.

FIG. 3 shows schematically a side view of another conical refiner partly in cross section.

FIG. 4 shows schematically a side view of a cylindrical refiner partly in cross section.

FIG. 5 shows schematically a side view of a disc refiner partly in cross section.

For the sake of clarity, the figures show some embodiments of the invention in a simplified manner. Like reference numerals identify like elements in the figures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a very schematic side view of a conical refiner 1 partly in cross section, which conical refiner 1 may be utilized to refine lignocellulose-containing wood-based fiber material. The refiner 1 has a first end Ea of smaller diameter and a second end Eb of larger diameter.

The refiner 1 comprises a stationary refining element 6, i.e. a stator 6, having a first end facing toward the first end Ea of the refiner 1 and a second end facing toward the second end Eb of the refiner 1, and therefore, for the sake of clarity, the reference sign Ea is also used to denote the first end of the stator 6 and the reference sign Eb is also used to denote the second end of the stator 6. The stator 6 is supported to a frame structure 5 of the refiner 1.

The stator 6 comprises a number of stator blade elements 7 having a refining surface 8, the refining surface 8 of each stator blade element 7 contributing to provide a complete refining surface of the stator 6. The stator blade element 7 has a first end facing toward the first end Ea of the refiner 1 and a second end facing toward the second end Eb of the refiner 1, and therefore, for the sake of clarity, the reference sign Ea is also used to denote the first end of the stator blade element 7 and the reference sign Eb is also used to denote the second end of the stator blade element 7.

According to an embodiment of the stator 6 it may comprise only one blade element 7 of a conical shape and extending over a whole periphery of the stator 6 so that the refining surface 8 of this single blade element provides a complete uniform refining surface of the stator 6. According to another embodiment of the stator 6 it may comprise at least two segment-like blade elements, i.e. blade segments that are arranged adjacent to one another whereby the refining surfaces 8 of the originally separate segment-like blade elements together provide the complete uniform refining surface of the stator 6. The term blade element, when referring to the stator 6 of the refiner 1, may thus refer to a single blade element providing the complete refining surface of the stator 6 or to a blade segment providing only a part of the complete refining surface of the stator 6. For the sake of clarity, the same reference number 8 may be used below to denote both the refining surface 8 of a single blade element 7 for the stator 6 as well as the complete refining surface 8 of the stator 6. The refining surface 8 in the stator 6 is typically provided with blade bars and blade grooves therebetween, an embodiment of some blade bars and blade grooves being shown later in FIG. 2.

The refiner 1 further comprises a rotatable refining element 9, i.e. a rotor 9, having a first end facing toward the first end Ea of the refiner 1 and a second end facing toward the second end Eb of the refiner 1, and therefore, for the sake of clarity, the reference sign Ea is also used to denote the first end of the rotor 9 and the reference sign Eb is also used to denote the second end of the rotor 9.

The rotor 9 comprises a number of rotor blade elements 10 having a refining surface 11, the refining surface 11 of each rotor blade element 10 contributing to provide a complete refining surface 11 of the rotor 9. The rotor blade element 10 has a first end facing toward the first end Ea of the refiner 1 and a second end facing toward the second end Eb of the refiner 1, and therefore, for the sake of clarity, the reference sign Ea is also used to denote the first end of the rotor blade element 10 and the reference sign Eb is also used to denote the second end of the rotor blade element 10.

According to an embodiment of the rotor 9 it may comprise only one blade element 10 of a conical shape and extending over a whole periphery of the rotor 9 so that this single blade element provides a complete uniform refining surface 11 of the rotor 9. According to another embodiment of the rotor 9 it may comprise at least two segment-like blade elements, i.e. blade segments that are arranged adjacent to one another whereby the refining surfaces 11 of the originally separate segment-like blade elements together provide the complete uniform refining surface of the rotor 9. The term blade element, when referring to the rotor 9 of the refiner 1, may thus also refer to a single blade element providing the complete refining surface of the rotor 9 or to a blade segment providing only a part of the complete refining surface of the rotor 9. For the sake of clarity, the same reference number 11 may be used below to denote the refining surface 11 of a single blade element 9 for the rotor 9 as well as the complete refining surface 11 of the rotor 9. The refining surface 11 in the rotor 9 is also typically provided with blade bars and blade grooves therebetween, as shown later in FIG. 2.

The rotor 9 comprises a hub 12 which supports at least one rotor blade element 10. The hub 12 is shown in FIG. 1, as well as in FIGS. 3 and 4 later, highly simplified. The hub 12 of the rotor 9 is connected to a shaft 13. The shaft 13 is connected to a highly schematically depicted motor 14 arranged to rotate the shaft 13 and, by the shaft 13, the rotor 9 for example in a rotation direction indicated with an arrow RD.

The refiner 1 may also comprise a loading device not shown in FIG. 1 for the sake of clarity, which loading device may be connected to the shaft 13 for moving the rotor 9 back and forth, as indicated schematically with an arrow AD, in order to adjust a distance between the stator 6 and the rotor 9, i.e. in order to adjust a size of a refining chamber 15 or a blade gap 15, forming between the stator 6 and the rotor 9 or the blade elements 7, 10 therein. The refining chamber 15 thus forms the volume wherein the fiber material is refined. The size of the refining chamber 15 relative to the other components of the refiner is exaggerated in all the figures. The refining chamber 15 has a first end facing toward the first end Ea of the refiner 1 and a second end facing toward the second end Eb of the refiner 1, and therefore, for the sake of clarity, the reference sign Ea is also used to denote the first end of the refining chamber 15 and the reference sign Eb is also used to denote the second end of the refining chamber 15.

The stator blade element 7 further comprises openings 16 a, 16 b extending through the stator blade element 7 and the rotor blade element 10 comprises openings 17 a, 17 b extending through the rotor blade element 10, the openings 16 a, 16 b, 17 a, 17 b thus extending through a whole thickness of the stator and rotor blade elements 7, 10. In an axial direction of the refiner 1, and therefore in an axial direction of both the stator blade element 7 and the rotor blade element 10, the axial direction indicated schematically by an arrow A in FIG. 1, the openings 16 a, 16 b in the stator blade element 7 are substantially at same axial positions with the openings 17 a, 17 b in the rotor blade element 10 when the blade elements 7, 10 are opposite to each other. Alternatively, the openings 16 a, 16 b in the stator blade element 7 could be at least partly different axial positions relative to the axial positions of the openings 17 a, 17 b in the rotor blade element 10.

Referring back to the embodiment of FIG. 1, the refiner 1 comprises at the first end Ea of the refiner 1 a first feed aggregate 18 a and a first feed channel 19 a connected to the first feed aggregate 18 a, through which first feed aggregate 18 a and the first feed channel 19 a a first fiber material fraction denoted schematically with an arrow FM1 is fed into a first feed chamber 20 a provided by an inner volume of the rotor 9 on the side of the first end Ea of the rotor 9. The first feed chamber 19 a extends from the first end Ea of the rotor 9 toward the second end Eb of the rotor 9 but not up to the second end Eb of the rotor 9.

The refiner 1 further comprises at the first end Ea of the refiner 1 a second feed aggregate 18 b and a second feed channel 19 b connected to the second feed aggregate 18 b, through which second feed aggregate 18 b and the second feed channel 19 b a second fiber material fraction denoted schematically with an arrow FM2 is fed into a second feed chamber 20 b provided by an inner volume of the rotor 9 on the side of the second end Eb of the rotor 9. The second feed chamber 19 b extends from the second end Eb of the rotor 9 toward the first end Ea of the rotor 9 but not up to the first end Ea of the rotor 9.

Furthermore, in the embodiment of FIG. 1 the refining surfaces 8, 11 in the stator 6 and the rotor 9 are designed or constructed in the axial direction AD of the refiner 1 such that in the refining chamber 15 there are two different refining zones with at least one different refilling surface characteristic in the axial direction AD of the refiner 1, i.e. a first refining zone 21 a at a side of the first end Ea of the refiner 1 and denoted with the arrow 21 a and a second refining zone 21 b at a side of the second end Eb of the refiner 1 and denoted with the arrow 21 b. In the axial direction AD of the refiner 1, the first refining zone 21 a is substantially at a location corresponding to the first feed chamber 20 a of the refiner 1 and a second refining zone 21 b is substantially at a location corresponding to the second feed chamber 21 b of the refiner 1. As shortly suggested above, at least one refining surface characteristic at the first refining zone 21 a is selected to be different from the respective refining surface characteristic at the second refining zone 21 b. Generally this means that the refining surface characteristics of the stator and rotor blade elements 7, 10 at the first refining zone 21 a are designed in view of the refining effect intended to be subjected to the first fiber material fraction FM1 to be refined at the first refining zone 21 a and the refining surface characteristics of the stator and rotor blade elements 7, 10 at the second refining zone 21 b are designed in view of the refining effect intended to be subjected to the second fiber material fraction FM2 to be refined at the second refining zone 21 b.

The operation of the refiner 1 of FIG. 1 is as follows.

The first fiber material fraction FM1 flows from the first feed chamber 20 a through first openings 17 a at the first refining zone 21 a into the refining chamber 15, whereby the first fiber material fraction FM1 is refined in the refining chamber 15 substantially at the first refining zone 21 a. The first openings 17 a thus connect the first feed chamber 20 a to the refining chamber 15 at the first refining zone 21 a. The first fiber material fraction FM1 is subjected in the refining chamber 15 at the first refining zone 21 a to the refining effect provided by the respective refining surface areas of the stator and the rotor blade elements 7, 10. The first fiber material fraction FM1 refined in the refining chamber 15 at the first refining zone 21 a is discharged out of the refining chamber 15 through first openings 16 a into a discharge chamber 22 at a background of the stator blade element 7. The first openings 16 a thus connect the refining chamber 15 to the discharge chamber 22 at the first refining zone 21 a. The flow of the first fiber material fraction FM1 into the refining chamber 15 and the flow of the refined first fiber material fraction FM1 out of the refining chamber 15 at the first refining zone 21 a is denoted schematically also with arrows FM1.

The second fiber material fraction FM2 flows from the second feed chamber 20 b through second openings 17 b at the second refining zone 21 b into the refining chamber 15, whereby the second fiber material fraction FM2 is refined in the refining chamber 15 substantially at the second refining zone 21 b. The second openings 17 b thus connect the second feed chamber 20 a to the refining chamber 15 at the second refining zone 21 b. The second fiber material fraction FM2 is subjected in the refining chamber 15 at the second refining zone 21 b to the refining effect provided by the respective refining surface areas of the stator and the rotor blade elements 7, 10. The second fiber material fraction FM2 refined in the refining chamber 15 at the second refining zone 21 b is discharged out of the refining chamber 15 through second openings 16 b into the discharge chamber 22. The second openings 16 b thus connect the refining chamber 15 to the discharge chamber 22 at the second refining zone 21 b. The flow of the second fiber material fraction FM2 into the refining chamber 15 and the flow of the refined first fiber material fraction FM2 out of the refining chamber 15 at the second refining zone 21 b is denoted schematically also with arrows FM2.

In the discharge chamber 22 the refined first fiber material fraction FM1 and the refined second fiber material fraction FM2 are combined, whereby they at least partly mix with each other. The combined flow of the refined first fiber material fraction FM1 and the refined second fiber material fraction FM2 is discharged out of the refiner 1 through a discharge channel 23 connected to the discharge chamber 22 and further through a discharge aggregate 24 connected to the discharge channel 23, as shown schematically with an arrow denoted with reference sign FM1+FM2. The combined flow of the refined first fiber material fraction FM1 and the refined second fiber material fraction FM2 is thus supplied as one flow to a further processing.

In the refiner 1 there are thus two refining zones 21 a, 21 b such that the first refining zone 21 a is specifically designed to refine the first fiber material fraction FM1 and the second refining zone 21 b is specifically designed to refine the second fiber material fraction FM2. The specific refining zone 21 a, 21 b characteristics are thus provided by specific design of the refining surfaces 8, 11 of the stator and rotor blade segments 7, 10 that contribute to provide the refining zones 21 a, 21 b. The advantage of this is that a single refiner may be used to simultaneously refine two separate fiber material fraction flows with at least one different qualitative characteristic, whereby specific portion in the refining surfaces 8, 11 of the stator and rotor blade segments 7, 10 is optimized to refine specific fiber material fraction. In other words, with the first refining zone 21 a with at least one different refining surface characteristic relative to the respective refining surface characteristic in the second refining zone 21 b it is possible to provide a single refiner to refine simultaneously two fiber material flows optimally.

According to an embodiment the first fiber material fraction FM1 and the second fiber material fraction FM2 are of one and same fiber material, i.e. of the same quality. In this case different portions of the same fiber material may be subjected to different refining effects at different refining zones 21 a, 21 b.

According to another embodiment the second fiber material fraction FM2 is qualitatively different from the first fiber material fraction FM1. With the definition that the second fiber material fraction FM2 is qualitatively different from the first fiber material fraction FM1 it is meant that at least one of a raw material, particle size, fiber length, freeness, residual lignin content and some other characteristic of the second fiber material fraction FM2 differs from the respective characteristic of the first fiber material fraction FM1. The hub 12 in the rotor 9 is constructed in such a way the first fiber material fraction FM1 in the first feed chamber 20 a and the second fiber material fraction FM2 in the second feed chamber 20 b do not mix with each other in the rotor 9.

According to a further embodiment the second fiber material fraction FM2 may be the first fiber material fraction FM1 that has been refined at the first refining zone 21 a and discharged out of the first refining zone 21 a. According to this embodiment the refiner is able to provide a two-stage refining for the first fiber material fraction FM1.

FIG. 2 shows schematically a plane figure of a blade element which is applicable to be used in the stator 6 of the refiner 1 of FIG. 1. FIG. 2 shows a single segment-like blade element 7 which is intended to provide a part of a complete refining surface 8 of the stator 6. FIG. 2 is intended only to exemplify possible different refining surface characteristics between the first refining zone 21 a and the second refining zone 21 b. For the sake of clarity only the segment-like blade element 7 for the stator 6 is disclosed in FIG. 2 but the same design principles apply also to the respective blade element 10 in the rotor 9 providing the counterpart for the stator blade element 7.

The blade element 7 of FIG. 2 comprises the first end Ea facing toward the first end Ea of the stator 6 and the second end Eb facing toward the second end Eb of the stator 6, and a refining surface 8. The blade element 7 further comprises two different refining surface areas, i.e. a first refining surface area 8 a on the side of the first end Ea and a second refining surface area 8 b on the side of the second end Eb. The first refining surface area 8 a is intended to provide the refining surface 8 of the stator 6 at the first refining zone 21 a of the refiner 1 and the second refining surface area 8 b is intended to provide the refining surface area 8 of the stator 6 at the second refining zone 21 b of the refiner 1. A fictitious divisional line between the first refining surface area 8 a and the second refining surface area 8 b is shown in FIGS. 1, 2, 3 and 4 with a broken line denoted with the reference sign DL. An axial direction AD of the blade segment 7 is denoted with a dot-and-dash line in FIG. 2.

The first refining surface 8 a of the blade element 7 comprises first blade bars 25 and first blade grooves 26 therebetween, as well as first openings 16 a extending through the blade element 7. The first blade bars 25 have a blade bar width W₂₅ and a blade bar angle α₂₅ relative to the axial direction AD, and the first blade grooves 26 have a blade groove width W₂₆. The first openings 16 a are round with a diameter of D_(16a). The second refining surface area 8 b of the blade element 7 comprises second blade bars 27 and second blade grooves 28 therebetween, as well as second openings 16 b extending through the blade element 7. The second blade bars 27 have a blade bar width of W₂₇ and a blade bar angle α₂₇ relative to the axial direction AD, and the second blade grooves 28 have a blade groove width W₂₈. The second openings 16 b are oval with a maximum diameter of D_(16b). In the schematic example of FIG. 2 it can be seen that the blade bar width, the blade groove width, the blade bar angle and a shape and size of the openings on the first refining surface area 8 a may be different from the blade bar width, the blade groove width, the blade bar angle and the shape and size of the openings on the second refining surface area 8 b. The shape of the openings may for example be round, oval, triangle or any polygonal shape. The size of the openings may vary largely from a minimum of a fiber length to a maximum of even half of the element length. The openings within an element may be like holes or perforations lying in the middle part between side edges of the element but they may also be like indents or cutouts at the side edges of the element.

The blade bar width, the blade groove width, the blade bar angle and a shape and size of the openings are some refining surface characteristics which may be varied when the refining surface characteristics are optimized for refining specific fiber material fraction with specific qualitative characteristics. A pitch of the refining surface, i.e. a common width of a single blade bar and of the single blade groove next to the blade bar, a blade bar height and a blade groove depth may be further characteristics which may be varied when the refining surface characteristics are optimized. When it is said above that the refining zones 21 a, 21 b have at least one different refining surface characteristic relative to each other, it is meant that at least one of those characteristics at one refining zone 21 a, 21 b differs from the corresponding characteristic at the other refining zone 21 a, 21 b.

According to an embodiment the first fiber material fraction FM1 may comprise virgin hardwood fiber pulp and the second fiber material fraction FM2 may comprise virgin softwood fiber pulp. In that case, on the first refining area 8 a of the blade element 7, i.e. on the first refining zone 21 a of the refiner 1, the first blade bar width W₂₅ could for example between 1 mm and 3 mm and the first blade groove width W₂₆ could for example be between 1 mm and 2 mm. On the second refining surface area 8 b of the blade element 7, i.e. on the second refining zone 21 b of the refiner 1, the second blade bar width W₂₇ could for example between 3 mm and 6 mm and the second blade groove width W₂₈ could for example be 2 mm and 5 mm.

The blade bars at the refining zone are set at such an angle that the blade bars promote the flow of the fiber material to be refined at the refining zone. In other words the blade bars set at such an angle provide a so called pumping effect on the fiber material to be refined at the refining zone. This kind of blade bar angle may for example be between 10 and 30 degrees. On the other hand, an angle of crossing, i.e. an angle between the blade bars in the rotor blade element and the blade bars in the stator blade element may be selected to be between 10 and 60 degrees, typically between 20 and 40 degrees.

In addition to the refining surface characteristics listed above, also the number of the blade bars as well as the blade gap 15 between the stator and the rotor may be different at different refining zones. In any case, the size of the blade gap 15 is less than 1 mm.

Furthermore, an area of a single refining zone in a blade element relative to an entire refining surface area of the blade element may vary between 10% and 90%, the rest of the entire refining surface area of the blade element being intended to be reserved for the at least one another refining zone in the blade element. This provides a possibility for the production of different kind of pulps. For example, when refining simultaneously the hardwood fiber pulp at one refining zone and the softwood fiber pulp at the other refining zone, the area of the refining zone intended to refine hardwood fiber pulp may for example be between 70% and 80% and the area of the refining zone intended to refine softwood fiber pulp may respectively be between 20% and 30%.

According to a further embodiment at least one of the refining zones 21 a, 21 b may be designed to have a very dense blade bar—blade groove—configuration, such as the configuration comprising the pitch of at most 3 mm, whereby a cutting edge length provided by the blade bars of the stator and rotor blade elements 7, 10 in the refiner 1 is very high. This, in common with a suitably selected opening configuration in the stator and rotor blade elements 7, 10, may have an effect that the degree of grinding of the fibrous material to be refined will be very high, even as high as that at least part of the refined material has particle size properties of nanofibrillar cellulose. The term “nanofibrillar cellulose” refers herein to a collection of separate cellulose microfibrils or microfibril bundles derived from plant-based, and especially wood-based fibrous material. Synonyms for the nanofibrillar cellulose (NFC) are for example nanofibrillated cellulose, nanocellulose, microfibrillar cellulose, cellulose nanofiber, nano-scale cellulose, microfibrillated cellulose (MFC) or cellulose microfibrils. Depending on the degree of grinding a particle size of the separate cellulose microfibrils or microfibril bundles is of some nanometers (nm) or micrometers (μm). A mean length of the separate cellulose microfibrils or microfibril bundles may for example be 0.2-200 μm and a mean diameter may for example be 2-1000 nm. The pitch of the blade elements and the total open area of the openings in the blade elements may be selected in combination such that the common cutting edge length of the blade bars in the refiner is even at least 50 km per one revolution of the rotor 7.

Furthermore, there may be different process parameters utilized at different refining zones 21 a, 21 b. The process parameters may for example comprise flow rate, pressure or pressure difference, consistency, pH-value and temperature.

The blade element of FIG. 2 may also comprise between the refining surface areas 8 a, 8 b, for example substantially at the fictitious divisional line DL, a dam arrangement preventing the first fiber material fraction FM1 to be refined and the second fiber material fraction FM2 to be refined to mix with each other in the refining chamber 15 at a border area of the refining zones 21 a, 21 b, if there is any tendency to such a mixing during the operation of the refiner and the mixing is not desirable.

The blade element of FIG. 2 is intended to cover the total length of the stator 6 in the axial direction AD of the refiner 1 but the blade element of FIG. 2 could also be provided of two different pieces, one of them comprising the first refining surface area 8 a and the other one comprising the second refining surface area 8 b.

FIG. 3 shows schematically a side view of another conical refiner 2 partly in cross-section, which conical refiner 2 may be utilized to refine lignocellulose containing wood-based fiber material. Correspondingly to the conical refiner 1 of the embodiment of FIG. 1, the conical refiner 2 of the embodiment of FIG. 3 comprises a first refining zone 21 a at a side of the first end Ea of the refiner 2 and a second refining zone 21 b at a side of the second end Eb of the refiner 2. The main difference between the refiner 1 of FIG. 1 and the refiner 2 of FIG. 3 is that the refiner 2 comprises a solid rotor blade element 10, i.e. the rotor blade element 10 of the refiner 2 does not comprise any openings extending through the blade element 10. As a consequence of that the refiner 2 of FIG. 3 does not comprise any feed chamber 20 a, 20 b but only the first feed aggregate 18 a and the first feed channel 19 a at the first end Ea of the refiner 2 and the second feed aggregate 18 b and the second feed channel 19 b at the second end Eb of the refiner 2. The first fiber material fraction FM1 is to be fed into the refining chamber 15 and the first refining zone 21 a therein through the first feed channel 19 a and the first end Ea of the refining chamber 15. The second fiber material fraction FM2 is to be fed into the refining chamber 15 and the second refining zone 21 b therein through the second feed channel 19 b and the second end Eb of the refining chamber 15. Otherwise the construction and operation of the refiner 2 of FIG. 3 and the refining surface characteristics may be similar to those disclosed above.

FIG. 4 is a very schematic side view of a cylindrical refiner 3 partly in cross-section, which cylindrical refiner 3 may be utilized to refine lignocellulose containing wood-based fiber material. The basic structure and operation of the cylindrical refiner 3 of FIG. 4 is substantially similar to that of the conical refiner 1 of FIG. 1 above, the main difference being the cylindrical form or shape of the stator 6 and rotor 9 instead of the conical shape. Because of this difference between the form or shape of the stator 6 and rotor 9 the size of the refining chamber 15 is adjusted in the cylindrical refiner 3 by adjusting the stator diameter, as indicated schematically with the arrow AD in FIG. 4. The structure and operation of the cylindrical refiner 3 of FIG. 4 is self-explanatory in view of FIGS. 1 and 2 and the description above.

In the refiners 1, 3 of FIGS. 1, 4 there are two different refining zones 21 a, 21 b in the axial direction AD of the refiner. The number of different refining zones in the axial direction AD of the refiners 1, 3 like in FIGS. 1 and 4 may be increased by increasing a number of the feed channels for the separate fiber material fraction flows.

FIG. 5 shows schematically a side view of a disc refiner 4 partly in cross-section. The refiner 4 of FIG. 5 comprises a first stationary disc-like refining element 6 a, i.e. a first stator 6 a, having a stator blade element 7 a and a refining surface 8 a therein. The refiner 4 further comprises a rotatable disc-like refining element 9, i.e. a rotor 9, next to the first stationary refining element 6 a, the rotor 9 having a first rotor blade element 10 a and a refining surface 11 a therein. The first rotor blade element 10 a and the refining surface 11 a therein are directed toward the first stator 6 a such that a first refining chamber 15 a is formed between the opposing refining surfaces 8 a, 11 a of the first stator 6 a and the rotor 9.

The refiner 4 of FIG. 5 further comprises a second stationary disc-like refining element 6 b, i.e. a second stator 6 b, having a stator blade element 7 b and a refining surface 8 b therein. The second stator 6 b is arranged next to the rotor 9 on the opposite side of the rotor 9 relative to the first stator 6 a such that the refining surface 8 a of the stator blade element 7 b in the second stator 6 b is directed toward the rotor 9. The rotor 9 has a second rotor blade element 10 b and a refining surface 11 b therein. The second rotor blade element 10 b and the refining surface 11 b therein are directed toward the second stator 6 b such that a second refining chamber 15 b is formed between the opposing refining surfaces 8 b, 11 b of the second stator 6 b and the rotor 9.

In the disc-like refiner 4 the refining elements 6 a, 6 b, 9 and the refining surfaces 6 a, 6 b, 11 a, 11 b extend in a radial direction R of the refiner 4, the radial direction R being substantially perpendicular to the axial direction AD of the refiner 4. Correspondingly the first refining chamber 15 a between the first stator 6 a and the rotor 9 as well as the second refining chamber 15 b between the second stator 6 b and the rotor 9 extend in a radial direction R of the refiner 4. In the radial direction R of the refiner 4 the stators 6 a, 6 b and the rotor 9, and the refining chambers 15 a, 15 b respectively, have an inner edge IE or an inner periphery IE and an outer edge OE or an outer periphery OE at opposite ends of the refining elements 6 a, 6 b, 9 and the refining chambers 15 a, 15 b.

Further in the refiner 4 of FIG. 5 there is a first feed aggregate 18 a and a first feed channel 19 a arranged to feed a first fiber material fraction FM1 into the first refining chamber 15 a through the inner edge IE of the first refining chamber 15 a. Further there is a second feed aggregate 18 b and a second feed channel 19 b arranged to feed a second fiber material fraction FM2 into the second refining chamber 15 b through the inner edge IE of the second refining chamber 15 b. The second fiber material fraction FM2 may be qualitatively different from the first fiber material fraction FM1 or they may be of one and same fiber material fraction. The refining surface characteristics of the refining surface 8 a of the first stator 6 a and the first refining surface 11 b of the rotor 9 forming therebetween the first refining chamber 15 a are selected according to the refining needs of the first fiber material fraction FM1, whereby the first refining chamber 15 a provides a first refining zone 21 a of the refiner 4. The refining surface characteristics of the refining surface 8 b of the second stator 6 b and the second refining surface 9 b of the rotor 9 forming therebetween the second refining chamber 15 b are selected according to the refining needs of the second fiber material fraction FM2, whereby the second refining chamber 15 b provides a second refining zone 21 b of the refiner 4. Due to the different refining needs of the qualitatively different fiber material fractions FM1, FM2 at least one refining surface characteristic in the first refining chamber 15 a is different from the respective refining surface characteristic in the second refining chamber 15 b.

Further in the refiner 4 of FIG. 5 there are two separate discharge chambers 22 a, 22 b. The first discharge chamber 22 a is intended to receive the first fiber material fraction FM1 refined in the first refining chamber 15 a, as shown schematically also with the arrow FM1. The second discharge chamber 22 b is intended to receive the second fiber material fraction FM2 refined in the second refining chamber 15 b, as shown schematically also with the arrow FM2. The refined first fiber material fraction FM1 is discharged out of the first discharge chamber 22 a through a first discharge channel 23 a and a first discharge aggregate 24 a. The refined second fiber material fraction FM2 is discharged out of the second discharge chamber 22 b through a second discharge channel 23 b and a second discharge aggregate 24 b. The refined first fiber material fraction FM1 and the refined second fiber material fraction FM2 are thus supplied as separate flows to a further processing.

In the refiner of FIG. 5 there is thus a discharge channel 23 a, 23 b respective to the refining zone 21 a, 21 b for discharging fiber material fractions having been subjected to different refining effects at different refining zones 21 a, 21 b as separate flows out of the refiner. Typically, the number of the discharge channels is the same as the number of the refining zones, i.e. one discharge channel for each refining zone but higher number of discharge channels at some refining zone is not, however, excluded. The refiner of this kind is especially useful in pulp manufacturing applications with moderate volumes of different fiber material fractions to be produced, allowing utilization of different fiber material fractions with moderate number of refiners but still with optimized refining effects subjected to the specific fiber material fractions.

In the refiner 4 of FIG. 5, instead of the separate discharge chambers 22 a, 22 b, the separate discharge channels 23 a, 23 b and the separate discharge aggregates 24 a, 24 b, also one common discharge chamber 22, one common discharge channel 23 and one common discharge aggregate 24 could be utilized. Correspondingly, in the refiners 1, 2, 3 of FIGS. 1, 3, 4 could also be utilized separate discharge chambers 22 a, 22 b, separate discharge channels 23 a, 23 b and separate discharge aggregates 24 a, 24 b, instead of one common discharge chamber 22, one common discharge channel 23 and one common discharge aggregate 24.

The refiner 4 of FIG. 5 is a double-disc refiner comprising two stators and a rotor therebetween, whereby two different refining chambers 15 a, 15 b are provided in the refiner. Similar type of construction may also be utilized in a conical refiner and a cylindrical refiner, whereby there are two conical or cylindrical stators and a conical or cylindrical rotor therebetween so as to provide two different refining chambers 15 a, 15 b, each of them providing a respective refining zone 21 a, 21 b with at least one different refining surface characteristic. This kind of refiner thus comprises a first stationary refining element and a rotatable refining element within the first stationary refining element and substantially opposite to the first stationary refining element such that a first refining chamber forming a first refining zone is formed between the opposing refining surfaces of the first stationary refining element and the rotatable refining element, as well as a second stationary refining element within the rotatable refining element and substantially opposite to the rotatable refining element such that a second refining chamber forming a second refining zone is formed between the opposing refining surfaces of the rotatable refining element and the second stationary refining element, and wherein at least one refining surface characteristic at the second refining zone is different from the respective at least one refining surface characteristic at the first refining zone. In this kind of conical or cylindrical refiners the first feed channel may be arranged to feed the first fiber material fraction into the first refining chamber through at least one end of the first refining chamber, and the second feed channel may be arranged to feed the second fiber material fraction into the second refining chamber through at least one end of the second refining chamber. The number of different refining chambers in this type of conical and cylindrical refiners, as well as in the type of disc refiners of FIG. 5, may further be increased by increasing the number of stators and rotors in the refiner.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims. 

I claim:
 1. A refiner for refining lignocellulose-containing fiber material, the refiner comprising: at least two substantially oppositely positioned refining elements each of said refining elements comprising at least one refining surface with blade bars and blade grooves, the refining surfaces of two substantially oppositely positioned refining elements facing toward each other and forming between them a refining chamber arranged to receive fiber material to be refined; at least two feed channels for feeding into the refiner at least one fiber material fraction to be refined; at least two refining zones with at least one different refining surface characteristic between the refining zones, each refining zone arranged to refine one fiber material fraction of the at least one fiber material fraction; and a discharge channel respective each of said refining zones for discharging fiber material fractions refined at the refining zones out of the refiner as separate flows.
 2. The refiner of claim 1 wherein the refiner further comprises: a first feed channel in the refiner connected to a source of a first fiber material fraction for feeding into the refiner; a second feed channel in the refiner connected to a source of a second fiber material fraction for feeding into the refiner; and a first refining zone in the refining chamber connected to the source of first fiber material fraction so as to refine the first fiber material fraction, and a second refining zone in refining chamber connected to the source of second fiber material fraction so as to refine the second fiber material fraction.
 3. The refiner of claim 2 further comprising a stationary refining element and a rotatable refining element within the stationary refining element and substantially opposite to the stationary refining element such that the refining chamber is formed between opposing refining surfaces of the refining elements, and wherein the refiner, the refining elements and the refining chamber have an axial direction defined by an axis of rotation of the rotatable refining element and in the axial direction along the refining chamber are at a first end of the refining chamber and in the refining chamber a first refining zone extending toward a second end of the refining chamber for refining a first fiber material fraction from the source of first fiber material fraction and at the second end of the refining chamber a second refining zone extending toward the first end of the refining chamber for refining a second fiber material fraction from the source of second fiber material fraction, the second refining zone having at least one different refining surface characteristic relative to the first refining zone.
 4. The refiner of claim 3 wherein the first feed channel is arranged to feed the first fiber material fraction into the first refining zone through the first end of the refining chamber, the second feed channel is arranged to feed the second fiber material fraction into the second refining zone through the second end of the refining chamber, and wherein the stationary refining element comprises at each refining zone at least one opening allowing the first fiber material and second fiber material refined at the respective refining zone arranged to discharge out of the refining chamber through the respective at least one opening.
 5. The refiner of claim 4 wherein the first feed channel is arranged to feed the first fiber material fraction into a first inner volume of the rotatable refining element through a first end of the rotatable refining element; wherein the second feed channel is arranged to feed the second fiber material fraction into a second inner volume of the rotatable refining element through a second end of the rotatable refining element; wherein the rotatable refining element comprises at each refining zone at least one opening allowing the fiber material fraction to be refined at the respective refining zone to be fed into the refining chamber at the respective refining zone through the respective at least one opening; and wherein the stationary refining element comprises at each refining zone at least one opening allowing the fiber material fraction refined at the respective refining zone to discharge out of the refining chamber at the respective refining zone through the respective at least one opening.
 6. The refiner of claim 2 wherein the refiner comprises a first stationary refining element and second stationary refining element with a rotatable refining element between the first stationary refining element and the second stationary refining element, the rotatable refining element having a first refining surface substantially opposite to a first refining surface of the first stationary refining element such a first refining chamber and a first refining zone is formed between the opposing first refining surface of the first stationary refining element and the refining surface of the rotatable refining element, and the second stationary refining element having a second refining surface such that a second refining chamber and a second refining zone is formed between the opposing second refining surface of the second stationary refining element and a second refining surface of the rotatable refining element, wherein at least one refining surface characteristic at the second refining zone is different from at least one refining surface characteristic at the first refining zone; wherein the refiner, the refining elements and the refining chambers have an axial direction defined by the rotation of the rotatable refining element, and in the axial direction a first end and a second end opposite to the first end; wherein the first feed channel is arranged to feed the first fiber material fraction into the first refining chamber through at least one end of the first refining chamber; and wherein the second feed channel is arranged to feed the second fiber material fraction into the second refining chamber through at least one end of the second refining chamber.
 7. The refiner of claim 2 wherein the refiner is a conical refiner with conical refining elements having a first end of smaller diameter and a second end of larger diameter.
 8. The refiner of claim 2 wherein the refiner comprises: a first stationary disc refining element and a rotatable disc refining element next to the first stationary disc refining element and substantially opposite to the first stationary disc refining element such that a first refining chamber forming a first refining zone is formed between the opposing refining surfaces of the first stationary disc refining element and the rotatable disc refining element; a second stationary disc refining element next to the rotatable disc refining element on the opposite side of the rotatable disc refining element relative to the first stationary disc refining element, the second stationary disc refining element being substantially opposite to the rotatable disc refining element such that a second refining chamber forming a second refining zone is formed between the opposing refining surfaces of the rotatable disc refining element and the second stationary disc refining element; wherein at least one refining surface characteristic at the second refining zone is different from the respective at least one refining surface characteristic at the first refining zone; and wherein the first feed channel is arranged to feed the first fiber material fraction into the first refining chamber and the second feed channel is arranged to feed the second fiber material fraction into the second refining chamber.
 9. The refiner of claim 6 wherein the respective discharge channel comprises a first discharge channel for discharging out of the refiner the first fiber material fraction refined at the first refining zone; and a second discharge channel for discharging out of the refiner the second fiber material fraction refined at the second refining zone.
 10. The refiner of claim 9 wherein the refining surface characteristic is at least one of the following: a blade bar width, a blade groove width, a blade bar angle, a blade bar height, a blade groove depth, a shape of an opening and a size of an opening.
 11. A method for refining lignocellulose-containing fiber material with a refiner comprising at least two substantially oppositely positioned refining elements comprising the steps of: feeding into the refiner at least two flows of at least one fiber material fraction to be refined; subjecting the at least two flows of the at least one fiber material fraction to different refining effects in the refiner to create a first refined fiber material fraction flow and a second refined fiber material fraction flow; and discharging the first refined fiber material fraction flow and the second refined fiber material fraction flow out of the refiner as separate flows.
 12. The method of claim 11 further comprising the step of forming the first refined fiber material fraction flow and the second refined fiber material fraction flow in a refining chamber between a stationary refining element and a rotatable refining element within the stationary refining element and substantially opposite to the stationary refining element; wherein the step of subjecting the at least two flows of the at least one fiber material fraction to different refining effects in the refiner to create the first refined fiber material fraction flow and the second refined fiber material fraction flow further comprises: sending a first fiber material fraction to a first refining zone of the refining chamber at a first end in a radial direction defined by the rotation of the rotatable refining element and refining said first refined fiber material fraction with a first refining surface, and sending a second fiber material fraction to a second refining zone of the refining chamber at a second and opposite end in the radial direction and refining said second refined fiber material fraction with a second refining surface which is different from the first refining surface; wherein the step of discharging the first refined fiber material fraction flow is by discharging out of the refining chamber at the first refining zone through at least one opening arranged in the stationary refining element at the first refining zone and wherein the step of discharging the second refined fiber material fraction flow is by discharging out of the refining chamber at the second refining zone through at least one opening arranged in the stationary refining element at the second refining zone
 13. The method of claim 12 wherein the first fiber material fraction to be refined is fed into an inner volume of the rotatable refining element through a first end of the rotatable refining element adjacent the first refining zone and into the refining chamber at the first refining zone through at least one opening arranged in the rotatable refining element at the first refining zone; and the second fiber material fraction to be refined is fed into an inner volume of the rotatable refining element through a second end of the rotatable refining element adjacent to the second refining zone and into the refining chamber at the second refining zone through at least one second opening arranged in the rotatable refining element at the second refining zone.
 14. A method as claimed in claim 12 wherein the second fiber material fraction is qualitatively different from the first fiber material fraction. 